Various structures and methods have been used to attach a handguard to a standard AR-pattern upper receiver, including some that secure the handguard to the barrel nut. However, unless mated with a proprietary design upper receiver, these typically involve the handguard having a longitudinal split that is drawn together to clamp it to the barrel nut. Such clamping requires flexing a portion of the handguard material, which can distort or weaken it.